1. Field of the Invention
An apparatus consistent with the present invention relates to a MEMS (Micro Electro Mechanical System) switch, such as an RF (Radio Frequency) switch, fabricated using a MEMS technique and, in particular, to a MEMS switch which is driven by using a piezoelectric element or actuator.
2. Description of the Related Art
Among RF elements using the MEMS technique, an RF switch is most widely fabricated. The RF switch is an element, which is used often in an impedance matching circuit or for selectively transmitting a signal, in wireless communication terminals and systems of microwave or millimeter wave band.
FIG. 1 is a top plan view exemplifying a structure of a conventional MEMS switch, and FIG. 2 is a cross-sectional view taken along line II-II′ of FIG. 1.
Referring to FIGS. 1 and 2, a signal line 3, which has contacts 3a spaced apart from each other by a predetermined distance, is formed on the middle of an upper surface of a substrate 2. Above the contacts 3a is located a movable electrode 6, which is supported by anchors 5. A contact member 6a is formed at the middle of the movable electrode 6 to connect the contacts 3a with each other.
A fixed electrode 7 is formed on the substrate 2 at both sides of the signal line 3, so that it generates an electrostatic force along with the movable electrode 6 therebetween and thus pulls and brings the contact member 6a of the movable electrode 6 in contact with the contacts 3a. 
According to the conventional MEMS switch constructed as described above, when a DC voltage is applied to the fixed electrode 7, the movable electrode 6 is charged with electricity, and thereby electrostatic force is produced between the movable electrode 6 and the fixed electrode 7. As a result, the movable electrode 6 is pulled toward the substrate 2. With the movable electrode 6 being pulled, both side portions of the contact member 6a, which is formed on the middle of the movable electrode 6, are placed in contact with the contacts 3a of the signal line 3.
However, the conventional MEMS switch has a structure in that both side portions of the contact member 6a are placed into contact with the contacts 3a of the signal line 3 during the operation. Such a structure not only increases the contact resistance, but also the insertion loss according thereto.